// Copyright 2013 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef UI_WM_CORE_DEFAULT_ACTIVATION_CLIENT_H_
#define UI_WM_CORE_DEFAULT_ACTIVATION_CLIENT_H_

#include <vector>

#include "base/compiler_specific.h"
#include "base/logging.h"
#include "base/macros.h"
#include "base/observer_list.h"
#include "ui/aura/window_observer.h"
#include "ui/wm/public/activation_change_observer.h"
#include "ui/wm/public/activation_client.h"
#include "ui/wm/wm_export.h"

namespace aura {
namespace client {
    class ActivationChangeObserver;
}
}

namespace wm {

// Simple ActivationClient implementation for use by tests and other targets
// that just need basic behavior (e.g. activate windows whenever requested,
// restack windows at the top when they're activated, etc.). This object deletes
// itself when the root window it is associated with is destroyed.
class WM_EXPORT DefaultActivationClient : public aura::client::ActivationClient,
                                          public aura::WindowObserver {
public:
    explicit DefaultActivationClient(aura::Window* root_window);

    // Overridden from aura::client::ActivationClient:
    void AddObserver(aura::client::ActivationChangeObserver* observer) override;
    void RemoveObserver(
        aura::client::ActivationChangeObserver* observer) override;
    void ActivateWindow(aura::Window* window) override;
    void DeactivateWindow(aura::Window* window) override;
    aura::Window* GetActiveWindow() override;
    aura::Window* GetActivatableWindow(aura::Window* window) override;
    aura::Window* GetToplevelWindow(aura::Window* window) override;
    bool CanActivateWindow(aura::Window* window) const override;

    // Overridden from WindowObserver:
    void OnWindowDestroyed(aura::Window* window) override;

private:
    class Deleter;

    ~DefaultActivationClient() override;
    void RemoveActiveWindow(aura::Window* window);

    void ActivateWindowImpl(
        aura::client::ActivationChangeObserver::ActivationReason reason,
        aura::Window* window);

    // This class explicitly does NOT store the active window in a window property
    // to make sure that ActivationChangeObserver is not treated as part of the
    // aura API. Assumptions to that end will cause tests that use this client to
    // fail.
    std::vector<aura::Window*> active_windows_;

    // The window which was active before the currently active one.
    aura::Window* last_active_;

    base::ObserverList<aura::client::ActivationChangeObserver> observers_;

    DISALLOW_COPY_AND_ASSIGN(DefaultActivationClient);
};

} // namespace wm

#endif // UI_WM_CORE_DEFAULT_ACTIVATION_CLIENT_H_
